He was a British artist, considered to be of the Neo-Romantic school. Allen was educated at Lancing College and then, on the recommendations of the artist Robert Anning Bell and art critic James Greig, at Byam Shaw School of Art, where he subsequently taught. He later lived and worked at Brightwell-cum-Sotwell, Wallingford, Oxfordshire, England.

Allen held a solo exhibition at the Walker's Galleries, London, in 1952, for which the catalogue's introductory essay was written by his fellow painter Brian Thomas. Pictures were purchased by T. S. Eliot, Sir John Betjeman, and The Earl Baldwin.The strain of the exhibition left him, after a while, unable to paint for eight years.

In 1973, after being asked to paint a tribute to Cardinal Newman, he converted to Roman Catholicism at Abingdon. He died in 1988.